The dual panel window screen alarm of the present invention generally resides in the field of audible alarms for detecting intrusion into a premises. More particularly, the invention pertains to removable window screens to which alarms have been attached.
There have not been any window screen alarms which are removable at will and are totally self-contained. Neither are any such apparatus available for sale at the present time. In researching previously described apparatus useful for providing an alarm at a window opening of a structure where the components of the alarm are mountable to a screen or mesh overlying the window opening, none were found that were removable from one opening and replaceable in another.
One recent attempt in providing a window screen alarm is described in U.S. Pat. No. 4,814,750 (Abramson). This patent describes an alarm system in which the screen is illustrated in two segments which appear to slide vertically relative to each other. The alarm system includes a self-contained, battery powered alarm circuit with an audible alarm means with both the circuit and audible/visual alarm elements mounted separate from the various wires covering the screen. From the written description, it appears that a magnetically responsive switch detects the removal of the screen from the window frame, or a "plug" connection may be broken by the same action of removing the screen from the frame, either causing the alarm circuit to trigger the audible/visual alarm mechanism.
An expandable entry detection apparatus is described in U.S. Pat. No. 5,103,208 (Riordan). The description is exemplary of an expandable alarm screen comprised of two frames which slide relative to each other in a horizontal motion. As in the case of the Abramson patent, the Riordan patent describes a screen which has alarm wires woven onto or through the mesh and connected through a common conductor to a "plug" means for connection to a separate alarm circuit mounted in the structure.
The disclosure in U.S. Pat. No. 3,051,935 (Willson) is similar to both of the patent descriptions discussed above in that a single screen has woven onto or in the mesh a series of alarm wires which are connected to an external alarm circuit set apart from the screen. The Willson patent is slightly different in that it describes a pair of contacts which complete the electrical circuit mounted on the window frame which contact the screen. Thus, removal of the screen, or cutting of any of the wires in the mesh, will trigger the alarm.
Another related apparatus is the intrusion alarm screen described in U.S. Pat. No. 4,839,632 (Zahn, Jr., et al.) which describes a window screen incorporating magnetic reed switches attached to interwoven alarm circuit wires on the mesh to detect removal of the screen from a framework, such as a window frame. The Zahn patent also discloses an alternate use of plug and socket connections for making the screen part of an entire house burglar alarm circuit.
None of these prior patents provide for a screen to which an audible alarm is attached which is entirely free standing (not attached to any structure alarm system) and does not have some form of interwoven alarm wires on or through the screen mesh.
It is, therefore, one object of the present invention to provide a self-contained screen alarm which is expandable to fit different sized window openings with the alarm detection means, control circuit, and audible alarm carried on-board the screen.
It is a further object of the present invention to provide a battery-powered screen alarm which is easily removed from one window opening and transferred to another.
It is a still further object of the present invention to provide an alarm detection means which is responsive to either the removal of the screen alarm from the window opening or the raising of the window without removal of the screen alarm.
Other objects will appear hereinafter.